Aircraft cabin and compartment for high altitude operation



March 5,1946. w. A. CUSTER r 2,395,852

AIRCRAFT CABIN AND COMPARTMEN'I' FOR HIGH ALTITUDE OPERATION Filed April 5, 1943 2 sheets-sheet 1 Fig.1

INVENTOR.

WARREN ANDERSON CU'STEIE v NW wwwd mfi ATTORNEYS March 5 1946. w ER' 2,395,852 f AIRCRAFT CABIN AND COMPARTMENT FfQR i-I I GH- AL'IITUDE OPERATION I Filed April 5, 1945 2 SheecIs-Sheet 2 I INVENTQR. WARREN ANDERSON CUSTER I ATTORNEYS Patented Mar. 5, 1946 AIRCRAFT CABIN AND COMPARTMENT FOR HIGH ALTITUDE OPERATION Warren Anderson Custer, Newtown, Pa. Application April 5, 1943, Serial No. 481,900

7 Claims.

This invention relates to the sealing of pressure cabins or compartments of aircraft for operation at high altitudes.

Difficulties are being experienced in the operation of aircraft at the high altitudes due to the lack of satisfactory methods and materials for sealing the pressure cabins and compartments for passengers and personnel of the operating force. The higher the craft rises into the substrate-v sphere or stratosphere, the lower the temperature becomes until it reaches the assumed constant of around about minus 67" F. Also due to the decreasing atmospheric pressure as thecraft ascends the differential in pressure between the pressure outside of the cabin and thepressure inside becomes larger as the altitude increases.

The temperature and pressure differentials be tween the interior of the cabin and the atmosphere outside of the cabin may vary over a wide range. For safe operation the cabin or compartment must be sealed against undue leakage between the interior and exterior thereof under the most extreme differences in pressures and temperatures arising in operation in order to preserve the oxygen supply, to maintain a living air pressure inside the cabin or compartment and to maintain livable temperatures inside the cabin or compartment. All closures and openings such as the doors, windows, hatches, emergency exits and openings through which controls and maneuverable objects, project must therefore be effectively and safely sealed under the most severe operating conditions.

One object of the invention is a novel and improved means and method for sealing or assisting in sealing the closures and openings of pressure cabins and compartments of aircraft for safe operation at the high altitudes.

A further object of the invention is a means and method for effecting the seal wherein the low outside temperatures and the differential in pressures between the inside and the outside of the cabin or compartment are utilized to assist in the maintenance of the seal and making the seal more effective.

From one aspect the invention resides in the utilization of a sealing material for the closures and openings of the cabin or compartment whose sealing capacity and effectiveness increase with the lower temperatures notwithstanding the higher diiferential pressures.

More particularly the means and method of this invention includes the use of a material about the closures which is fluid at ordinary room temperatures but whose viscosity increases at the higher altitudes congeals or tends to congeal to form a substantially solid but elastic and flexible seal against the interchange inside andoutside.

A further object of the invention is a seal of theabove described character comprising means operable at will to reduce or control the viscosity of the sealing material to impart to it the desired degree of fluidity and one means for effecting this purpose is a suitable electrical heating elementor elements disposed in heating elation with the periphery of the closure and the sealing material thereabout. V

In the preferred embodiment of the invention the sealing material which is a sealing fluid at ordinary or room temperatures is caused to flow while in the fluid condition around the boundary or peripheral edge of the closure, where it is retained to assist in maintaining a tight seal. This preferred material has the property as indicated,

of an increase in viscosity with the'lowering of p the temperature so that upon exposure to the lower temperatures of the outside air experienced in plane operation in the stratosphere, and

= in a manner to act as an effective yieldable or V flexible seal as soon as a differential in pressure exists between the inside and outside of the cabin or compartment. This differential in pressure tends to cause the fluid or semi-fluid sealing material to creep outwardly but such a difference in pressure is accompanied by very much lower temperatures on the outside with the result that the sealing fluid is influenced by the lower temperatures of the outside and thereby tends to become more viscous and better enabled to withstand the relatively high pressure in the fuselage, while the inner and less viscous portion of the, sealing medium which is less aifected by the outside temperature tends to be crowded into tight sealing p 5 The incorporation of heating means such as elecrelation under the influence of the pressure difference. The sealing fluid or material is disposed intermediate the inner and outer surfaces of the cabinwall and at a point where itis subjected to or influenced by the outside temperatures.

of air between the I Fig. 1 is a perspective view of thelinterior of a part of a fuselage or airplane compartment embodying the invention; 7 i

Fig. 2 is a section along the line 2 2 of Fig. 1; Fig. 3 is a sectional viewon 'anenla'rged scale; Fig. 4 is a view of a heating circuit diagram;

and H Fig.5 isfajyiew of an embodiment of-the invenltionjas appliedfto the. sealing of closures 'for maneuverable objects such as guns.

.,-.''Referring to Figs. l-3, a section of the fuselage binflor. compartment of a high altitude craft, h theivalls of the compartment diagrammatl lyindica'ted, is designated by the numeral]. rh e'apens into the compartment a door 3 which fis hinged at the hinges 5-5 'for inward swin'g'ing a and. openingfmovemjerits... A suitable'latch T4 is 1 video. for locking the door in closed position. .flfhefsides anattp "edges of thewall forming the opening for 'the door which may be referred to as the doorjarnb, are formedion the interior with iz cii r i fe the re p c? e. c ree n n ge 20 iormed about the interior edge of the 1.93. .Similarly, the door 3 is provided with a as in ec'c e 'iqiih t t fi ti es- ,and flanges above described for securing a tight de s'ii i i er et lii e a emp a u ips i iei. This c sm es m a s on h o a ihede rii mb 9 nc c emlicrhcldinc 1. .ei. i i e ete el wh iefl d a di cr p'er u ese d te to ec er v,yi 9011s .or less fluid at higher temperatures so toassist iniorming the sealthough its physie gche. ect ris ce h n i h h n s te per' ure'conditions such that it tends tobecome id this sealing substance.or material does .not at any time impair or injure the structure. ta le m erie h n th c a e ti .pbci'egdeeqribed;may be emp o ed: .A. pa t c larly suitable material is being marketed under she ira ezname Thnube h s e r elhe t in rs ca l re rty cf b n a u d or ry. or 41 m t mp r tur s. 15 bec mi m r vis the em eratu i lcw ccle d c c. eee1, n int auefi t ye sea in mat i at tem rat r je cqu r li he .su st ato h e crammsphere It also has the property as indicated, -.Qf; e yi i dfie b e w e co a d Sc asnot to injure the structure being sealed and cess preferably going all the way around the cess around itsquter edge to accommodate a 7 go f filling clearances or crevices between the surwhat depend nau c th .P i iQ ll E 3121 9 i c .of Ehe-pe r n 'nci i imarvar rcmi i h ly below zero Fahrenheit temperature to around with other grooves extending down the si minus 60 F. and by pouring point I mean the temperature below which the material will not flow, but as indicated above, the material even at those low temperatures still, has some degree of pliability. It is understood that I am not limited to any specific formula or composition of a usable material for my purpose but the following are examples of materials having different visi cos'ities which may be used in different applicatioIis:

Example 1.--To prepare a composition having ."a viscosity substantially the same as glycerin or a medium motor oil dissolve in to parts of dibutyl iphthalate 0.9 to 1.0 parts of we nitrocellulose (1000 second). Such cotton ordinarily contains approximately 30% solvent.

Example.2.To illustrate the efiect of the viscosity of the cotton on the viscosity of the final product a material which is substantially the same as that described in Example l may be prepaifedby dissolving 2 to 215 parts wet? nitrocellulose (15 second) in 90 to100 'par'ts dibu'tyl phthalate. I v .Erahiplejih material having "a viscosity at ordinary, temperatures which approximates that of GQOQN greasemay be prepared by dissolving A to Biparts of 100 second nitrocellulose in 90 to 100 pa ts of dibutyl phthalate.

. "Example 4.A material havinga viscosity approaching that of a'thin cup grease may be made advantageously by dissolving "4 to 16 parts 1( 1000 seeped) cotton in 90 to 100 parts of dibut'yl phth'alat'e.

t .Egm'mple '5.-' -To illustrate'the manner'of niodifying theproperties oi the solution of the cotton in ithecotto'n solvent onemay employ a composition such asith'at formed by following thedirecltior'is'setlforth in Examples 1 0112. Upon heating 6.5 ounces of this'composition to approximately 80 C.Iw ith2 su t s a: aluminum stearate :ahdTlZ tuiicestr toluol a clearjell is obtained of "a con- "sistencyfapproximating.Vaseline.

' lof' theiinvention to'limit'the use of asealing ina- "term- V a A lubricant a -viscosity index of around .120 and .a pour point.of=..2 0 I. may Iisedand Thalube materials are particularly suitable due to lthefiacflthatfthey can be easily adapted to the mechanical and .teifiperatiire requirements of the members of'tlie'lcabin thatjaretojbe'sealed,

'Forthe' purpose of accommodating and retaining this sealing substance oiiejor bothtit e structural members isprovi'de'd .i'yith .a 'grbsve or grooves "extending Y'around the edge of the door and the dooriafiib, and in the particu'ar'embodimentshown infFig. 1, llhaveillu'st'rated a pair of grooves ([2 extendin along the top mating edges of the door andthe jamo. x Theseigr ooves |'2 coinniuriidate at theiriien'ds ans h I c n .-.ie i b e i i s-c i' c f e ce w lrc i es' r "she i cie t e c. h-i the door and jainb. "Pre'ierablythe're aretwo grooves similar to 12 all around the closure which are spaced from each other some distance as indicated in Fig. 2 so as to provide two separate and spaced sealing grooves .all the way around the door. If desired, single grooves only may be provided. Where the two grooves l2 extend all the way around the door jamb, an opening 22 represents a passage or clearance connecting thetwo separate grooves l2. With this passage or groove 22 connects a passage 23 formed in the wall of the compartment and leading through a pipe M to a container or reservoir 6 for the sealing material. A container 9 for the sealing fluid is illustrated to supply the fluid to the grooves formed in the upper edge of the door or jamb. Gravity may be utilized for supplying the fluid to the closure in which case as illustrated, the reservoir 9 is disposed above the level of the upper edge of the door. This reservoir communi cates at the bottom through a pipe II), II with a passage 24 formed in the wall above the closure and leading to the grooves l2.

The sealing fluid is initially contained in reservoir 9 and is supplied from thereto the door and door jamb for sealing the same. From the door jamb the fluid passes through the pipe M to the reservoir 6. The fluid may be pumped up from the reservoir 6 to the reservoir 3 through the pipe 8, a pump I being illustrated for this purpose. The pipe I3 is provided with a suitable valve indicated by the letter V for shuttingofl the supply to the grooves. ilarly provided with a valve to retain the sealing fluid in the door or door jamb. The reservoir 6 i may be provided with any suitable pressure control valve [5.

The door is illustrated as shown inFig. 3 as having side walls 26 and 27 which are spaced from each other by means of frame members 28, the side walls being fastened to the frame members 28 forming the periphery of the door in any suitable manner as for example by screw bolts 29. The door and other closures may be provided 'with any heat and cold insulating means between the side walls 26 and 21.

In Fig. 3 the grooves I2 are illustrated as being joined by a passage or by a clearance extending all the way across the width of the door frame 28.

In Figs. 3 and 4 I have also illustrated a means for heating and rendering the congealed sealing material a fluid. This means comprises the electrical heating elements l1 disposed in the grooves l2. It is also of advantage to have an electrical heating element l8 embedded in the door jamb adjacent the outer-most groove l2 and the outer wall surface so as to facilitate thesoftening of the sealing material. These heating elements I! and 18 preferably extend all the way around the door jamb.

I have also shown in Fig. 3 a means for supplying electric current to the heating coils I1 and 18. This means comprises a conventional electric plug 30 for connection with the source of current. This plug 3!) is comprised in a, nipple it which may be screw threadedly attachedto the open end of the pipe II and preferably a pipe or tube 3| is carried by this nipple for leading conductors, not shown, to the. electric heating elements. In Fig. 4 I have shown a conventional battery 32 and circuits for supplying the heating elements I! and Ill. The heating coils I! may be divided into two or more branches with switches 33 controlling-these heaters and av The pipe I4 is simsimilar switch 33 shown for cutting in and out the heater l8. Y

.In the embodiment of the invention in Fig. 5 I have shownthe invention as applied to the sealing 5 of the opening in the wall through which a maneuverable gun or other object projects, such a as the object indicated at 35. This gun 35 is carried by a section 36 of asphere which is mounted in a spherical surface formed in the opening in the wall I of the compartment. For facilitating the assembly a plate 31 is attached to the wall I and is fastened thereto by the screw bolts 38.

A part of the spherical surface cooperating with the spherical member 33 is formed in the plate 31 and the member 36 is retained in the operative position with the maneuverable device '35 projecting out through the wall I and maneuverable universally to point in different directions. The spherical surfaces of the wall are provided with grooves l2 extending all the way around the spherical member 36 and are joined at the bottom by a passage 33 which in turn communicateswith the passage 23 which leads to the outlet pipe I4. The sealing fluid is taken in through the pipe H and may be caused to flow all the way around the spherical member 35 to occupy the sealing grooves either by gravity or pump means. It is also preferable to have the grooves l2 joined by a passage or clearance intermediate the same at the top so as to provide for distribution from the top. It is understood that controlv valves are disposed in the pipes H and M for shutting off the supply of fluid and preventing the flow of fluid from the sealing grooves. Electric heater means such as I! and I8 may be associated with the grooves and the sealing material therein to control its viscosity as in the modification of Figs. 1-4.

With members that protrude through the pressure cabin to the outer atmosphere it may also be desirable to use a sealing medium of a somee what higher viscosity than that of the fluid used to seal those parts of the cabin that would ordinarily remain closed or immovable during flight in the stratosphere or substratosphere. For this purpose one could use a lubricant or material that would have a higher pour point say around -10 but one that would have a low rate of shear. The electrical resistance could be regulated so that it would heat the area which it contacts to a point above the pour point of the lubricant and thus accomplish a fluid seal. This type of adjustment in the sealing medium would be particularly adaptable to the uses in the universals used in swivel gun mountings (Fig. 5) or in the channels-sealing revolving gun turrets or in the sealing of those operating openings from the cabin to the members of the aircraft external to the control cabin by which the controls are operated by mechanical motion from within the cabin.

A number of greases or lubricants known to those'familiar to the art of lubrication could be employed in this application of the invention and the viscosity and viscosity index and rate of shear of the sealing medium to be used in any such instance would be determined by themechanical, pressure and temperature conditions that would exist at the point and the action of the protruding member to be sealed.

I have illustrated and described above one specific method and means for heating and controlling the viscosity of the sealing material, namely an electric resistance heating means. It is understood that other heating means may be used such as heating by electric induction, by fluid conthalt'the phase heating means used ih th'e eams .is intended to cover all alternative aiiZl-siiit'able.

heating means for controlling the viscosity of the material except where specifically limited to *"resi'stan'ce heaters.

in some applica'tidhsbf the inventionas above indicatedit is advantageous to use as a sealing ihe'dium' one that will 'n'ot flow at the temperatures under which it "is operated. nowevenin forder to maintain an 'effectives'al of the cabin it is desirable to introduce into 'the 'medium an {electrical resistance or heatingelement *s'o that a portion or this medium can be ma ntained m a fluid state in theareas surroundingthe hatirig element so as to prevent by 'means dr thisfluid meal-any leakage of air pressure from inside *the u Thus by the correlation andus'e oi assume l'ieatin'g means with sealing material coming within'the scope of my invention "and having-a definite Viscosity'at one-temperature, the viscosity ofthis'se'ali'ng medium may be -readily controlled and'varied. In the embodiment of the invention shown 'in Fig. 5, it is preferable to use a m'aterial of a higher viscosityat agiven temperature than that of thematerial best"suitejd "ior th'e embodinientof Figs. 2an'd'3, -and-"since the rate of shear or the-sealing medium utilizedin Fig-5 "would in *that case be lower than that or the preferred niediu'm usedin the embodiments ofFigs. 2 ans 3,

'it'is advantageous to utilize the heating means such 'as the electric heating means I I to'maintain a-portion of the sealing medium in a-fluid state or semi-fluid "state under operatingcondi-tions to effect sealing. Otherwise if the element were moved while the sealing medium was not in a 'fiuidor semi-fluid condition, leakage-might occur, since the sealing medium immediately adjacent the-"surface of the movable element would not flo'w to maintain theseal; In such cases it "is Particularly importantto maintainthe temperathreat that part ofthe sealing medium which is in contact with'thembymg 'imentabbve the pour point.

iatedwith the passages-cs, 24 'and the 'pip'es s oc p fl} and 'M '60 Heat BIIld facilitate the how fofthe sealing mediumlthereth rough. Thishpassess-2 sermon of pressures on the outside and inside of the cabinorcompartment as "the craft "as- -cends.

2. A' seal-fora closure member for an opening :a pressure cabin orcompartment of an aircraft operable at high altitudes, comprising a groove about the closure and the opening and a sealing mediuin'disposed in said groove which --is a fluid at "ordinary temperatures and has the property of becoming more highly viscous with "decreasing temperatures over a wide temperature range from ordinary temperatures down to thelow ltemperatures encountered at high altitudes and of congealing at the lower temperatures into a solid body which is yieldable and free from cracks and brittleness and remains -'so 'at the low temperatures encountered in the sub-stratosphere, said seal thereby offering increasing resistance to the increase of the diiferential 'of pressures on-the outside and insideof the cabin or compartment as the craft ascends, the said sealing medium having a pouring point between 0 F. and -'67 F.

3. A seal fora closure 'memberfor'an opening in a pressurecabin or compartment of an air;

craftoperable at high altitudes, comprising a groove about the closure and the opening and a sealing medium'disposed in said groove which 'isa fluid at ordinary temperatures and has the property of becoming more highly viscous with decreasing temperatures over a wide temperature range from ordinary temperatures down to the low temperaturesencountered at high altitudes and of congealing at the lower temperatures into a solid'body which is yieldable and free from cracks and brittleness and remains so at the low temperaturesencountered in the sub-stratosphere, said seal thereby offering increasing resistance to the increase-of the differential of pressures-on the outside and insideof the cabin or compartment as the craft ascends, and heatingmeans for controlling the viscosity of said sealing medium.

'4.- Apressure'cabin or compartment for aircraft of the character set forth in claim 1 comprising electrical heating meansffor controlling the --viscosity of said sealing medium.

-5.Aseal for-a elosure'member 'for-an opening in a pressure cabin or compartment of an aircraft operable at high altitudes, comprising a-groove=aboutthe closure and the opening and -a-sealing medium disposed in saidgroove which -is a fluid at ordinary temperatures and has the property of becoming-more highly viscous with decreasing temperatures over a wide tempera- ;ture range from ordinary temperatures down to the-low temperatures encountered at high alticraft operable 'at'highaltit'ud'es, 'comprisin'ga :groove about 'the clo'ure" and" the"operiing and; a setting medium disposed in" said "gr ov "which "is a fiuid at ordinary temper-staccato has the "property or becoming more highly viscous with decreasing temperatures over "a wide temperature range from ordinary tempera ure -down to the lowtemperatures' encountered*at"high alititudes and of con'gealing' at the "lower" temperatunes into asoIidbody whichis"'yielclable*and tree from cracks and trauma-seam frenrains "so" at i the low tempei'atures encoun red in fthe sub-stratosphere, sail-.1- seal thereby rering i creasing resistance to the increase of the diftudes andof congealing at the lower temperatunes into asolidb'o'dy which is yieldable and free 'from'cracks and brittleness and remains so at the low temperatures encountered'in the sub-stratosphere, said seal thereby offering increasing "resistance 'to theincrease of the differential? "pressures" on the outside and inside of the cabin or compartment as the craft ascends, the said sealing medium comprising a "highboilingpoint'esterdissolved into a liquid solvent having J a low freezing point.

' 6. A'sealfora closure'member for an opening "in apressure cabin or compartmentof an air- "craft' operable at high altitudes, comprising a "groove 'about'the closure and the opening and ase'aling medium 'disposed-in said groove-which "is a fluid at ordinary I temperatures "and has the property of l becoming more highly viscous with small quantity of nitrocellulose dissolved into a v relatively large quantity of dibutyl phthalate.

F]. A seal for a closure member for an opening in a pressure cabin or compartment of an aircraft operable at high altitudes, comprising a groove about the closure and the opening and a sealing medium disposed in said groove which is a fluid at ordinary temperatures and has the property of becomingmore highly viscous with decreasing temperatures over a wide temperature range from ordinary temperatures down to the low temperatures encountered at high altitudes and of congealing at the lower temperatures into a solid body which is yieldable and free from cracks and brittleness and remains so at the low temperatures encountered in the sub-stratosphere, said seal thereby offering increasing resistance to the increase of the differential of pressures on the outside and inside of the cabin or compartment as the craft ascends, and comprising spaced grooves containing said sealing medium.

WARREN ANDERSON CUSTER. 

